Reading Military Standard Nut, Washer, and Screw Families
Several Military Standard prefixes anchor a single hardware type across a full range of sizes: one prefix identifies the family, and the dash number picks out the specific variant within it. Recognizing the family a designation belongs to is the fastest way to place an unfamiliar part number before resolving it to a full federal record.
MS19070 and MS19068 — key washers and their companion nuts
MS19070 anchors a family of key washers — a locking washer with a small tab that engages a matching slot on the mating part, resisting rotation without relying on thread friction alone. MS19068 anchors the companion round nut that family is typically ordered against, keyed the same way. The two prefixes turn up together for exactly that reason: specifying one keyed-washer designation usually means its size-matched nut designation is needed as well.
MS19068-051 (NUT,PLAIN,ROUND) — NSN 5310-00-185-6426
MS35206 — machine screws
MS35206 anchors a range of machine screws. As with every dash-number system on this site, the prefix identifies the governing specification; the length, thread, and head-style variant within that specification is carried by the dash number and confirmed against the part's federal record, not read off the digits directly.
MS51957 — machine screws
MS51957 anchors a second, distinct machine-screw series under the same identification model — prefix identifies the family, dash number identifies the specific variant, and the NSN it resolves to carries the confirmed technical characteristics.
How the dash number varies within a family
Across all four families here, the number after the dash is not a size you can decode by formula — it's an index into that standard's own dimensional table, fixing size, thread, material, and finish for that one variant. Two dash numbers under the same prefix can differ by a single dimension or by several at once; the only reliable way to tell them apart is the published standard or the item's resolved NSN, not the shape of the number itself.
Identifying and cross-referencing any family
Whichever of these four prefixes a drawing or a bill of materials calls out, the identification path is the same: the MS number resolves to an NSN, and the NSN's federal record carries the item's technical characteristics, manufacturer cross-references, and supersession history where it applies. Atlas Air Supply stocks and quotes this hardware against its governing specification under CAGE 224F0, with the full federal record available before a quote is requested.